Loose Leaf

The Official Blog of American Forests

A Petrified Site

Have you ever had a connection to an object that’s difficult to explain?

Sitting on the mantle in my childhood home is a hunk of rock that on the surface is just a large, heavy, brownish thing. It resembles a trunk; it’s round and tall and polished to a high gloss — and I’ve loved it for as long as I can remember. Why? Because it’s not the simple brownish rock it appears to be. It’s a piece of agatized petrified wood that was collected on private property in the Wind River Range in western Wyoming and has been in my family for generations.

And while my family’s petrified wood was found in Wyoming, another place with petrified wood — possibly the most famous in the country, if not the world — celebrated two special anniversaries over the weekend. On Dec. 8, 1906, President Theodore Roosevelt created Petrified Forest National Monument in Arizona to protect the fossilized remains of an ancient Mesozoic forest. More than 50 years later, on Dec. 9, 1962, the national monument became Petrified Forest National Park.

What is petrified wood exactly? Simply, it’s wood that has turned into a mineral. The complicated answer is that more than 200 million years ago — in the case of Petrified Forest National Park — pieces of ancient trees were rapidly buried under large amounts of sediment and debris by the area’s rivers. This process prevented oxygen from reaching the wood so instead of decaying, the wood’s pores began to absorb dissolved minerals over time, thus turning the wood from wood to mineral.

But Petrified Forest is more than just a paleontological smorgasbord. Located approximately 100 miles to the east of Coconino National Forest, which houses many of our national champion big trees, Petrified Forest is one of the largest areas of grassland in the Southwest, supporting a wide variety of grasses, lichens, wildflowers and even a few tree species and shrubs. It’s also home to a wide variety of animals from owls to snakes and lizards and even a turtle species!

So, happy anniversary to this archeologically rich grassland wonder. May it provide the same kind of fascination to others as a piece of petrified wood has held for me.

In the fall, cottonwood turn golden along the Puerco River in Petrified Forest National Park. Credit: Hallie Larsen/NPS